Electrical brush



- April 23, 1957 .J. v. CAPUTO ETAL 2,790,100

ELECTRICAL BRUSH Filed June 6, I951 IN V EN TORS JAMES V.CAPU THOMAS J. CRAW RD.

ATTOR N EYS United States Patent ELECTRICAL BRUSH James V. Caputo, Youngstown, Ohio, and Thomas J. Crawford, Berkley, Mich.

Application June 6, 1951, Serial No. 230,152

7 Claims. (Cl. 310-427) The present invention pertains more especially to the collecting brushes for dynamo-electric machines and has for a principal object to provide liquid cooled brushes especially useful where high density direct current flows through the brush as for example a homopolar generator for supplying heavy pulses of current for relatively short intervals for welding as disclosed in our copending application Serial No. 780,170, filed October 16, 1947, now Patent No. 2,600,844 of which this application is a continuation-in-part.

Our invention may be more fully understood by reference to the accompanying drawings in which Fig. 1 is a fragmentary view of a portion of a collector ring of a dynamo-electric machine, brush holding bar and a brush holder with a brush therein on the bar, the brush bearing against the collector ring. The view is a transverse section through a portion of a homopolar generator;

Fig. 2 is an elevational view of a brush removed from the holder;

Fig. 3 is a similar view with a slightly modified form of brush.

Referring now more specifically to the drawings, 2 designates the rotatable collector ring of a dynamoe1ectric machine asfor example a homopolar generator of the type shown in said copending application and in my prior -U. S. Patent No. 2,005,609. Extending along the collector ring 2 area plurality of brush holding bars 3, one of which is shown in Fig. 1 and on which are securely mounted metal brush holders 4. The metal brush holders include an ofiset socket 5 having a notch 6 in one Wall thereof. The socket is of a size to receive the brush 7 which is of generally rectangular section and which is relatively longcompared to its section. For purposes of clarity the usual mechanism for holding the brushes in the sockets and exerting endwise pressure on the top thereof is not shown but such equipment is disclosed in my aforesaid copending application.

The brush itself is a molded body constituted of a suitable conducting material. We preferably use a bonded mixture of carbon or graphite and metallic copper dust with the copper dust predominating. A particularly desirable composition is one made up from 90% of 300 mesh copper and 10% of 300 mesh graphite compacted and sintered to a density of 90 to 95% of the density of the basic materials.

In the construction shown in Fig. 2 the brush is provided with an internal passage 8 of generally U-shape form or C-shape form, the passage having two legs extending longitudinally and connected by a cross passage 8a. The passage extends longitudinally from the end of the brush remote from the collector ring contacting end toward the collector ring contacting end but terminates in advance of the ring contacting end of the brush. It terminates sufiiciently far back from the ring contacting end of the brush to permit a substantial wearing away of the end of the brush without approaching too close to cross passage 8a. In order to limit the movement of 7 2,790,100 Patented Apr. 23, 1957 the brush so that it can never wear down to a point where the water pressure would break through the end of the brush, one or more lugs 9 are formed on the side of the brush and which enter the notch or notches 6 in the top of the brush holding receptacle 5. As the brush wears away the lug 9 approaches the lower end of the slot 6 as viewed in Fig. 1 eventually contacting the end of the slot to prevent further relative movement of the brush in the receptacle. The inner terminal 8a of the passage is so positioned with reference to the lug that the lug reaches the limit of its travel in the slot wall in ad,- vance of the time when the brush has worn down to a length where there would be danger of the liquid used to cool the brush from breaking through at the wearing end of the brush.

Two tubes 10 connected to a circulating source of liquid are secured to the end of the brush remote from the wearing end, these tubes registering with the vertical legs of the passage 8. One tube provides for the influx of liquidand one for the outflow of liquid.

A coolant is circulated through the passage at a pressure at around 1 to 10 pounds per square inch. A certain amount of the coolant, be it water or oil, will find its way through the brush from the passage 8 and provide moisture to the wearing face of the brush. The use of the coolant and the presence of water at the working face of the brush not only enables the brush to carry a current of heavy density, but it provides a condition conducive to the formation of an oxide film on the surface to form a closed passageway in the body back from the working end of the brush. In this figure, 13 designates the brush and 11 are the two intersecting passageways with the point of intersection bein'g marked 11a. With this brush as in the one shown in Fig. 2 one or more lugs would be provided on the exterior of the brush member for limiting the extent to which the brush can be worn away as previously explained.

Tubes 12 are entered into the ends of the two passageways 11 and provide for the circulation of liquid through .the brush inthe manner hereinbefore described. The

main difference in the two structures is the shape of the coolant passageway within the body of the brush.

While we have shown and described certain specific embodiments of our invention and have described the brushes as being of a certain preferable composition, it will be understood that our invention is not restricted to the particular construction shown or to the use of the particular materials and the changes and modifications are contemplated within the scope of the appended claims.

We claim:

1. A brush for a dynamoelectric apparatus comprising an elongated current conducting member having one end portion thereof adapted to make sliding contact with a second current conducting member and having an opposite end portion, a substantially U-shaped fluid conducting passageway within said opposite end and having its substantially parallelly extending portions opening outwardly of said opposite end, and material spacing said passageway from said one end portion whereby said passageway will be continually spaced from such second current conducting member, said brush comprising a :zymonuo 3 material which will transmit liquid by absorption to the end which makes sliding contact with the second current conducting member.

2. A brush for a dynamoelectric apparatus comprising an elongated current conducting member having one end portion thereof adopted to make sliding contact with a second. current conducting member and having an op posite end portion, means providing a continuous fluid flow passageway spaced from said one end and having an inlet and an outlet located adjacent said other end portion, said brush being of a composition providing a closed passageway for the cooling fluid, but of a character through which some fluid may be absorbed and conducted to the working end of the brush.

3. A current collecting brush for use in a brush holder having a guiding surface, a first elongated current conducting member having a first portion adapted to make sliding contact with a second current conducting member and having a surface adapted to rest against such guiding surface and to be movable therealong to com pensate for wear at said first portion, means providing a fluid flow passageway within said first conducting member and spaced by said one member from said second member, said first member having inlet and outlet means spaced from said first portion, and means carried by said first member and cooperable with such holder to hold said first member against sufiicient movement toward said second member to maintain said passageway spaced from said second member.

4. In a current collecting apparatus, a cylindrical rotatable current conducting means, a supporting brush holding member having a brush supporting recess, a brush slidably carried in said recess and having a means at one end engaging the surface of the rotatable current conducting means and a portion spaced from said surface, said brush having an internal coolant flow passageway with inlet and outlet openings, said coolant fiow passage extending toward but not to the end which carries said means for engaging the rotatable conducting means, means urging the brush toward said rotatable conducting means, stop means cooperable with said brush. and supporting brush holding member and arranged to limit movement of said brush toward said rotatable current conducting means so positioned that upon Wearing of the brush which engages the rotatable current conducting means, the innermost end of such passageway will be spaced outwardly from the rotatable current conducting means.

5. A current collecting brush comprising an elongated member which is substantially rectangular in cross section and which is provided with a first end portion for slidable contact with a current conducting element and provided with an opposite end portion, said member having a pair of intersecting passageways extending generally lognitudinally of said member and opening outwardly 4 through said opposite end portion, and an abutment on said member and cooperable with a brush holding member and so positioned with respect to the passageway as to prevent the brush wearing down to the passageway.

6. A current conducting brush for electrical apparatus comprising an elongated current conducting member having a first end wall adapted to make sliding contact with a current conducting element and having a second end wall at the opposite end thereof, said member having an internal passageway with an inlet and an outlet through i second end wall, said passageway being positioned in .aid member such that within the limits of expected wear of said member said passageway will be continually spaced from the first end wall, said member being formed of compacted carbon with metallic dust therein and being comprised substantially of about of 300 mesh copper and l of 300 mesh graphite compacted and sintered to a density of from 90% to of said copper and graphite.

7. A brush for dynamo-electric apparatus comprising an elongated current conducting member having a contact engaging end and having two tubes entered in the opposite end thereof with a passageway in the member leading from said tubes toward but not to the contact engaging end of the member, said tubes providing connections for passing a cooling liquid through said passageway in the member wherein said member permits a capillary flow of liquid therethrough from the passageway to the contact engaging surface of the member.

References Cited in the file of this patent UNITED STATES PATENTS 533,931 Thomson Feb. 12, 1895 738,478 Phillips Sept. 8, 1903 1,066,175 Barry July 1, 1913 1,188,761 Hambuechen June 27, 1916 1,281,716 Trood Oct. 15, 1918 1,298,726 Jackson Apr. 1, 1919 1,335,141 Turbayne Mar. 30, 1920 1,612,337 Wilson Dec. 28, 1926 1,635,581 Meadowcraft July 12, 1927 2,103,931 Berger Dec. 28, 1937 2,181,076 Siebenmorgan Nov. 21, 1929 2,194,620 Sekyra Mar. 26, 1940 2,319,240 Larson May 18, 1943 2,548,631 Stapleton Apr. 10, 1951 2,557,075 Caputo June 19, 1951 FOREIGN PATENTS 24,751 Great Britain of 1907 115,704 Austria Jan. 10, 1930 490,375 Germany Jan. 27, 1930 832,471 France July 4, 1938 

